diff --git a/companion_scripts/02_create_database/03_create_reference_database.R b/companion_scripts/02_create_database/03_create_reference_database.R
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+#' @title reference list
+#' @description create a data.frame of the equation references
+#' @details This script compiles the list of publications from which the
+#'   equations in the equation database were compiled
+#' @author James G. Hagan (james_hagan(at)outlook.com)
+#' 
+
+# load relevant libraries
+library(dplyr)
+library(readxl)
+
+# load the reference list
+ref_dat <- readxl::read_xlsx(path = "C:/Users/james/OneDrive/PhD_Gothenburg/Chapter_4_FreshInvTraitR/data/allometry_database_ver4/reference_database.xlsx")
+head(ref_dat)
+
+# check the database
+View(ref_dat)
+
+# replace the NA characters with true NAs
+ref_dat[ref_dat == "NA"] <- NA
+
+# export the database as a .rds file
+saveRDS(ref_dat, "database/reference_database.rds")
diff --git a/database/reference_database.rds b/database/reference_database.rds
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